Aim
The purpose of this study was to evaluate the usability of three established VSP software applications (IPS Case Designer ®, Dolphin Imaging ®, and ProPlan CMF ®) regarding the virtual planning steps of midfacial correction using modified IQLFIIO. Specific aims were to compare feasibility, time consumption, and costs in a standardized workflow.
Design
Based on retrospective data, we performed a cross-sectional study and re-planned all patients with midfacial deficiency treated by modified IQLFIIO and BSSO (bilateral sagittal split osteotomy) at our institution between April 2013 and December 2018 using the three software applications: IPS Case Designer ®, Dolphin Imaging ®, and ProPlan CMF ®.
The study sample was recruited from a consecutive series of patients with midfacial deficiency treated by modified IQLFIIO and BSSO. Inclusion criteria were midfacial deficiency and skeletal class III malocclusion as well as a fulfilled protocol with pre-surgical and post-surgical orthodontic treatment. The surgical treatment had to be completed at the time point of the beginning of the study. Exclusion criteria were missing or poor quality of available pre-surgical computer tomography (CT) data.
This study was approved by the ethics committee of the authors’ institution (No. EK 1775/2017) and performed according to the Declaration of Helsinki and the guidelines for Good Clinical Practice (GCP).
Data acquisition—virtual surgical planning
In this retrospective study, all cases were re-planned by VSP with three different software application systems. The pre-intervention data were obtained from existing CT or cone-beam CT (CBCT) examinations of the head. VSP was done with the software applications IPS Case Designer ® (KLS Martin Group), Dolphin Imaging ® 11.95 (Patterson Dental Supply, St. Paul, MN), and ProPlan CMF ® (Materialise). A routine workflow for VSP for IQLFIIO was performed. This included data import of Digital Imaging and Communications in Medicine (DICOM) datasets, rendering a 3D image of the head, setting the intervention cut lines for IQLFIIO, calculating the surgical intervention of the 3D model for hard and soft tissue. The last step was virtual model surgery by moving the maxilla including the infraorbital region into the target position.
All VSP were performed with a personal computer—Dell Inspiron 15 5000 Notebook (Intel Core i5-7500 U, 16 GB RAM, 256 GB SSD, AMD Radeon R7 M445) by one experienced person who had been trained on all three applications.
Variables
To evaluate and compare feasibility, the following steps in the process of VSP of an IQLFIIO were evaluated: (i) preselect a IQLFIIO tool, (ii) setting of cut lines on defined IQLFIIO landmark positions (maxilla, infraorbital rim, anterior nasal spine), (iii) 3D rendering of the segment to be moved, (iv) act of moving to the target position, and (v) possibility to design a splint.
In order to establish a standardized and realistic procedure, post-surgical intervention results were defined as the target position for the VSP. Distances between pre- and post-operative landmarks were measured in a previous step to import exactly these movements into the VSP system. These data were obtained by image fusion using Materialise Mimics ® Research 21.0 (Mimics-Materialise NV Belgium). These measurements were used to set the target position in all three compared VSP systems.
The IQLFIIO cut lines were set in positions corresponding to the post-operative CT scans. The 3D rendered model was cut exactly along these lines. The selected IQLFIIO part was moved into the target position by manual input of the known distances. All the measurements and VSP have been done by one researcher who has been experienced and trained in using these software tools consequently.
Regarding time used for the VSP, the time of the surgeon working with the PC was measured for all steps of the VSP procedure in minutes (min).
Regarding costs, asset costs for acquiring the software application, license fee, license possibilities, paying for support services, service contracts, and costs for splint production in cooperation with the VSP system were covered by contacting the company. Costs were calculated in dollars ($) without value-added tax.
Data analysis
For characterizing the study, cohort descriptive statistics was used. All data were recorded in Microsoft Excel 2017.
The purpose of this study was to evaluate the usability of three established VSP software applications (IPS Case Designer ®, Dolphin Imaging ®, and ProPlan CMF ®) regarding the virtual planning steps of midfacial correction using modified IQLFIIO. Specific aims were to compare feasibility, time consumption, and costs in a standardized workflow.
For the graphical analysis of time consumption, a boxplot graphic was created. For comparison time consumption, a post hoc analysis with a Tukey range test was performed.
Statistical analysis was performed using the open source software R Project R 3.1.1. The costs are outlined in tables.